The African snakebite 'crisis' is nothing new: we’ve been worried about antivenom for decades

This article by Anita Malhotra,  of our School of Biological Sciences was originally published on The Conversation. Read the original article.

There is a sound reason why snakes have a reputation for being among the world’s most dangerous animals. In Africa alone, there may be more than 1.5m people a year who find themselves on the receiving end of snakebites. Without access to the only effective treatment, antivenom, the death rate can be as high as 20%, with survivors often suffering life-changing disability.

This snakebite antidote is made by collecting the antibodies produced by animals such as horses when they are injected with venom. Injecting more than one snake’s venom can produce a “polyvalent” antivenom, effective against multiple types of bite. One of the most useful antivenoms in Sub-Saharan Africa is Fav-Afrique, which works against bites from ten different species - helpful when you don’t know what kind of snake bit you.

A 20-year crisis

International charity Médecins Sans Frontières recently warned that Africa was facing a crisis since the company Sanofi-Pasteur stopped making Fav-Afrique last year, leaving enough supplies to last only until 2016. Sanofi-Pasteur claims it has been priced out of the market by cheaper products.

But it’s hard to understand why the prospect of Fav-Afrique finally running out next year should precipitate a crisis now when it only provided around 500 treatments annually, and the decision to cease production was announced by the company as long ago as 2010. Recent analysis of the market showed that in 2011 Sanofi Pasteur had the lowest annual production among the eight producers of African antivenom and among the highest costs per treatment. The authors found the industry could increase antivenom production from around 80,000 treatments to as many as 600,000 if capacity was fully used, while bringing down the price due to economies of scale.

The reality is that Africa has had a snakebite antidote crisis for almost two decades, since another major manufacturer, Behringwerke, ceased antivenom production. Action has been taken, although not at the level of global health authorities such as the World Health Organisation, which has been criticised for its historic neglect of the issue of snakebite. Several new antivenoms have come into use in an attempt to fill the large gap between supply and projected demand.

But availability of suitable antivenom is only one of the issues that limits its use where it is most needed by the predominantly poor, rural, Africans who get bitten. Thea Litschka-Koen from the charity Antivenom Swazi told me:

Doctors don’t use (antivenom) because there is nothing to use. It is so expensive, only the super-rich countries and individuals can afford it. Millions of people receive free anti-retroviral drugs for life, but we can’t afford to treat snakebite, which is a medical emergency.

She added that the availability of a number of different antivenoms on the market does not help the situation as doctors are confused about which to use.

The value of Fav-Afrique

The real value of Fav-Afrique was that it was known to be effective and could be widely used across Africa. Not all antivenoms marketed for the Africa are the same. Sometimes this means a larger dose is required, bringing greater risk of adverse reaction and a higher bill. In the worse cases, however, the antidote may be incapable of neutralising the specific venom from the bite.

Some types of snake kill many more people than others, such as the carpet vipers of the genus Echis, which are found from the west coast of Africa right across the Middle East to India. But to make an effective antidote it is not enough to simply include the venom of any type of Echis, as deadliness to humans and the specific toxins in them vary considerably between species. Despite this, some of the antivenoms marketed in Africa are produced with the venom from an Indian species and have proved ineffective against some of the most deadly types of Echis.

This means that some products that appear to fill the gap left by the withdrawal of Fav-Afrique would be worse than useless if they did not work because their failure could decrease confidence in using antivenom at all.

The good news is that the new antivenoms on the market, including a Pan-African antivenom with the same coverage and claimed efficacy as Fav-Afrique produced by a new antivenom company in India may be capable of filling the gap. What is needed now is rapid provision of funding to carry out proper evaluation and comparison of these treatments. A relatively modest sum in relation to other health campaigns might be all that is needed. However, solving other problems, such as distribution, storage, and faith in the treatment requires the active participation of local governments and global health organisations, and may be more difficult to solve.

Publication date: 10 September 2015